Purchasing a Gram Scale

[stevenje]

I am looking to buy a gram scale for the darkroom. Any recommendations on which one to buy?
Thanks in advance.

 

[xkaes]

There are a ton to choose from. You first need to decide what the maximum weight you will ever need to weigh. The smaller the less expensive. Then decide how fine a measurement you want -- 1gr, 0.1gr, 0.01gr, etc. The finer the more expensive. Then do you want digital or analog. You can get a lot of great USED analog scales for next to nothing because everyone wants digital. But analog never needs batteries.

I use an Ohaus CENT-O-GRAM. Up to 311 grams (11 ounces), and measures to 0.01 gr.

 

[fgorga]

I wanted a small portable scale so I did not have to drag my AC powered lab-grade digital balance to a workshop I was teaching.

Thus. I bought this one... https://www.amazon.com/dp/B07DJBDL6L a month ago. 500 g capacity , 0.01 g resolution which is good enough for most alt process work.

It got a heavy workout during the day long workshop without a hitch.

 

[mshchem]

The old Ohaus "high-school science " mechanical balances work great. Nothing with springs. The Ohaus Harvard Trip balance is terrific for mixing powders. A small electronic scale for tiny amounts comes in handy. I bet I have a dozen different balances.

 

[Randy Stewart]

I assume your purpose is to weigh out bulk chemicals to prepare processing formulas. I've done this for more than 40 years, using a traditional Ohaus Triple-Beam Balance scale. This scale resolves to 0.1 gram, and is completely adequate for any photo formula. Modern digital technology gives us small platform scales for around $20, which resolve the same and work bout as well. They are cheaper and easier to use. Available on-line or in any office supply store (postal scale). No photo process requires more precision or expense.

 

[RalphLambrecht]

I am looking to buy a gram scale for the darkroom. Any recommendations on which one to buy?
Thanks in advance.

I use one with a maximum capacity of 300g and a read-out resolution of 0.01 g. Unfortunately, it is just labeled as 'Digital Scale.' it was inexpensive and works great. 300 g is about the maximum quantity you need in a small darkroom. I bought another with a max of10g and a resolution of 0.001 g, which I need for a few chemicals, of which one only needs trace amounts. Both are available from Amazon.

 

[gbroadbridge]

Remember. Resolution is not the same as accuracy.

There are many cheap digital scales out there that display to 0.01g but whose accuracy is around +/- 0.1 gram

 

[mshchem]

Remember, make it as complicated as possible!

 

[drew tanner]

A $15 Cen-tech pocket scale from Harbor Freight has worked fine for me for several years. Accurate to 0.1g, which is close enough for anything I’m mixing in the darkroom.

 

[RalphLambrecht]

Remember, make it as complicated as possible!

very true

 

[mshchem]

A $15 Cen-tech pocket scale from Harbor Freight has worked fine for me for several years. Accurate to 0.1g, which is close enough for anything I’m mixing in the darkroom.

I have something similar I bought at a coin shop. I use it to check US 1 cent coins. Copper weighs more than the plated zinc. It would be great for weighing small amounts. I have a 40 year Sartorius top loading digital scale, made in Germany (that's old) very nice. Doesn't hurt to have a couple check weights around.

 

[bdial]

I use this 500 gram scale daily for prepping coffee, https://shop.kingarthurbaking.com/items/pico-high-precision-scale.
It’s 8 or so years old, needs batteries once a year. I test it occasionally with a balance weight, it’s always right on.
It only gets used in. the kitchen though, for the darkroom I have an Ohaus triple beam.

 

[mshchem]

I use this 500 gram scale daily for prepping coffee, https://shop.kingarthurbaking.com/items/pico-high-precision-scale.
It’s 8 or so years old, needs batteries once a year. I test it occasionally with a balance weight, it’s always right on.
It only gets used in. the kitchen though, for the darkroom I have an Ohaus triple beam.

I should consider weighing my beans. I used too generous volume measures the other morning and I was bouncing off the walls.

 

[koraks]

Any recommendations on which one to buy?

The best one $20 can buy you on Amazon/AliExpress etc.
It really doesn't matter; all these low-end 'jewelry' scales from China are perfectly fine for darkroom use.

 

[wiltw]

Many kitchen scales can do both Metric and Imperial units...but if wanting tenths of gram measurement precision, you might need to look elsewhere.

 

[grahamp]

Balances Don't over think it. Modern electronic balances are good enough, just find one with at least 0.01g display resolution, and a big enough pan to hold weighing paper and the bulk of your typical chemicals. Get a couple of metal spatulas while you are at it - I favour a scoop end for larger volumes, and a small blade type for fine adjustments.

Look at the 'recipes' you may want to make, that will inform your choice.

I was taught on 4 and 5 figure mechanical laboratory balances. Capable of incredible accuracy, but slow to use, and needed a climate controlled space. This was doing analysis below 1 part per million. Photo chemistry is closer in scale to baking a cake

 

[MCB18]

I got a $20 100g scale that displays 0.01g accuracy. I have found that it works extremely well, even for measuring stuff like 0.12g of chemistry.

 

[Nitroplait]

Remember. Resolution is not the same as accuracy.

There are many cheap digital scales out there that display to 0.01g but whose accuracy is around +/- 0.1 gram

I think above deserves to be repeated.

0.01g on the display is resolution - not (likely) accuracy. And especially not trustable with a cheap scale.

Scales are not easy to make accurate AND cheap.

A scale that has a range of say 0-1000g is definitely NOT going to be accurate to the 0.01g resolution through-out that range and most likely not 0.1g or even 1g..

Best to get a scale that can be calibrated and one that operates close the target weight you want to measure.

If you need to measure accuracy at fractions of a gram, get a scale that covers 0-50g or 0-100g.
Get another scale for larger volumes.

Some scale manufactures are more honest than others.
The most useful and trustable scale I own is made for coffee brewing - but also perfect for most of my darkroom measurements:
Hario VST-2000
It measures from 2g to 2000g.

The display will resolve 0.1g up to 200g, 0.5g up to 500g, and 1g up to 2000g

The assured accuracy range is +- 0.2 up to 200g, +-1g up to 500 and +-3g up to 2000g (at a room temperature of 20C +-5degrees)
If a container with very warm liquid is put on the scale the accuracy decline by up to additional +-2g.

These are not amazing specifications, but they are trustable and importantly they are disclosed with the product.

 

[gbroadbridge]

I got a $20 100g scale that displays 0.01g accuracy. I have found that it works extremely well, even for measuring stuff like 0.12g of chemistry.

The is zero chance that a $20 scale is accurate to 10 milligrams (0.01g) no matter what it is showing on its display..

 

[Chan Tran]

I have this one. By itself it's capable of 1100g with 1g resolution. With enough weighs it can do up to 20kg. With the weighs I have there it can do 6100g. I think it's accurate to +/-1g but it's a pain to use.

 

[MCB18]

The is zero chance that a $20 scale is accurate to 10 milligrams (0.01g) no matter what it is showing on its display..

It does come with some calibration weights (10g, 5v, 1g) all of which show the correct weight, so it’s probably good enough.

 

[Nitroplait]

It does come with some calibration weights (10g, 5v, 1g) all of which show the correct weight, so it’s probably good enough.

Well, as long as 0.12g is not critical for your purposes, then it may be fine.

 

[BobUK]

I got fed up of digital scales becoming twitchy.
Two small ones for tenths of grams, and a larger digital kitchen scales consigned to the bin.

Like xkaes I now have a Cent-O-Gram accurate to 1/100 of a gram.
Also a Harvard single beam balance for larger weights.

The second hand Cent-O-Gram tests accurate when compared with a set of laboratory weights. The sort that have very fine weights that look like tiny offcuts of cooking foil.

The larger Harvard is also accurate compared to the lab. weights.

Although the scales are left unused with a dust cover over them, a useful thing to remember is to leave them unbalanced when not in use. A small weight on the pan to stop the balance oscillating if left in a draughty location. The idea is to stop unnecessary wear on the knife edges.
I think this idea is actually mentioned in the Ohaus Instructions.

 

[BobUK]

It's Horses for Courses.

Accurate scales when required, but for fixer I just use plastic disposable cups marked appropriately for sodium thiosulphate etc. and spoon measures.

 

[gbroadbridge]

It does come with some calibration weights (10g, 5v, 1g) all of which show the correct weight, so it’s probably good enough.

How do you know that those references are correct?